title: Cold exposure down-regulates zebrafish pigmentation.
abstract: Vertebrates use adaptive mechanisms when exposed to physiologic stresses. However, the mechanisms of pigmentation regulation in response to physiologic stresses largely remain unclear. To address this issue, we developed a novel pigmentation model in adult zebrafish using coldwater exposure (cold zebrafish). When zebrafish were maintained at 17 °C, the pigmentation of their pigment stripes was reduced compared with zebrafish at 26.5 °C (normal zebrafish). In cold zebrafish, gene expression levels of tyrosinase and dopachrome tautomerase, which encode enzymes involved in melanogenesis, were down-regulated, suggesting that either down-regulation of melanin synthesis occurred or the number of melanophores decreased. Both regular and electron microscopic observation of zebrafish skin showed that the number of melanophores decreased, whereas aggregation of melanosomes was not changed in cold zebrafish compared with normal zebrafish. Taken together, we here show that cold exposure down-regulated adult zebrafish pigmentation through decreasing the number of melanophores and propose that the cold zebrafish model is a powerful tool for pigmentation research.
authors.affiliation: Department of Hematopoietic Stem Cells, SSP Stem Cell Unit, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Kasem
authors.initials: K
authors.lastname: Kulkeaw
authors.forename: Tohru
authors.initials: T
authors.lastname: Ishitani
authors.forename: Takaaki
authors.initials: T
authors.lastname: Kanemaru
authors.forename: Ognen
authors.initials: O
authors.lastname: Ivanovski
authors.forename: Midori
authors.initials: M
authors.lastname: Nakagawa
authors.forename: Chiyo
authors.initials: C
authors.lastname: Mizuochi
authors.forename: Yuka
authors.initials: Y
authors.lastname: Horio
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sugiyama
mesh_terms: D000818:Animals; D003080:Cold Temperature; D015536:Down-Regulation; D050883:HSC70 Heat-Shock Proteins / Q000378:metabolism; D019746:Intramolecular Oxidoreductases / Q000378:metabolism; D008547:Melanophores / Q000378:metabolism*; D014442:Monophenol Monooxygenase / Q000378:metabolism; D012880:Skin Pigmentation / Q000235:genetics / Q000502:physiology*; D015027:Zebrafish / Q000254:growth & development / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000378:metabolism*
chemical_list: D050883:HSC70 Heat-Shock Proteins; D029961:Zebrafish Proteins; C494374:hspa8 protein, zebrafish; D014442:Monophenol Monooxygenase; D019746:Intramolecular Oxidoreductases; C042501:dopachrome isomerase